Plankton are an important part of food chains in marine environments. They provide food to small fish as well as to large mammals like baleen whales. Plankton is a term including drifting, tiny organisms--plants, animals, algae, bacteria and archaea. Phytoplankton live in the photic zone, the place in the ocean that light penetrates and can support photosynthesis. Zooplankton feed on other plankton and bacterioplankton help with decomposition and recycling materials in the sea. Because plankton is generally small, a huge amount of plankton can be supported by the sea provided enough light is available and nutrients are in the water necessary for their survival. However, only a few thousand large fish can be supported by the same area, because their nutritional needs are larger and they have to expend energy in order to find food. This is the pyramid of energy as well as the pyramid of numbers. As you go from the producer level, up to the consumers, ending with a top level consumer, the shape of the pyramid from bottom to top, gets narrower. This represents the numbers of organisms at each level. The producers are vast as they support the herbivores, which in turn, support the carnivores. Top level carnivores would be the least in number, in any food pyramid. Think of how much plankton a huge whale would have to consume, in order to stay alive and maintain its body!